Radiation curable compositions are beginning to gain industry acceptance. In order to cure radiation curable coatings high radiant fluxes are required on the order of 5 W/cm2 or higher at the surface. These high radiant fluxes are typically generated with high flux energy sources including electron beam energy sources, mercury vapor light energy sources, which emit radiation in radiation including ultraviolet A (UVA) radiation (315 nm to 400 nm), ultraviolet B (UVB) radiation (280 nm to 315 nm), ultraviolet C (UVC) radiation (100 nm to 280 nm), and infrared (IR) radiation (700 nm to 1000 nm). Moreover, these high radiant flux energy sources are dangerous and require UV shielding to protect the operator and passerby's from UV light. Finally, the high radiant flux energy sources cannot be used with temperature sensitive substrates, e.g., substrates that are sensitive to high temperatures.
Besides the high radiant fluxes required to cure conventional radiation curable compositions. The conventional radiation curable compositions cannot cure to be tack free and are tacky after radiation curable due to oxygen inhibition. In practice, this requires using a nitrogen blanket in order to properly cure these UV compositions.
A need exists for a system and method for using VOC free low radiant flux LED UV curable composition.